Process for preparing photographic films



J. H. HAs 'E PROCESS FOR PREPARING PHOTOGRAPHIC FILMS Filed April 14. 1924 6 L a C a e 5 O I m d C,

Gelatinous sul mstmtu'm Fla l Sensitive emu1s1on 4 Cellulose ester yywm To all whom it may concern Fetented Apr. 7, 1925.

UlTED STT rarest 1.53am Fries.

JAMES H. HSTE, OI ROCHESTER, YORK ASSIGINOR TO EASTMAN KODAK COM- IANY,'OFROGHESTER, NEW 'YQIRK, A CORPOBAT IQN OF NEW YORK.

PROCESS FOR FREPARING 'PHOTOGRAIHIC Application a April 14, 1ea4.. seria1no. 706,378.

Be it known that I, JAMns H. HASTE, a

citizen of the United States of America, re-

siding at Rochester, in the county of Menroe and State of New York, have invented certain new and useful Improvements in Processes for Preparing Photographic Films, of which the following is a full, clear, and exact specification.

This invention relates to processes for preparing photographic films and is applicable to (but not limited to) the preparation of films of the type dis-closed in my prior application, No. 591,862, filed Oct. 2, 1922 for composite film, of which the present application is a continuation in part.

One object of the invention is to provide a process for the rapid and economical production of a composite photographic film in which the several layers are made to adhere with especial tenacity and without destroying said layers. hereinafter appear.

In the accompanying drawing,-

Fig. 1 is a fragmentary cross section, uppn an exaggerated scale, of one form of m which may be produced by my process;

Fig. 2 is a diagrammatic elevation upon an exaggerated scale of one form of apparatus in which the steps of my process may be conveniently carried out.

In the manufacture of photographic films in which the gelatino-silver halid'emulsion layer is carried 'upon a laminated base or support,:the layersof which comprise cellulosic materials such as cellulose nitrate and cellulose acetate, it is essential for the best results to have all the layers adhere with reliable firmness so ,that they will not become separated when subjected I to the action of photographic liquids, when drying, or when subjected to theheat of projection apparatus. This is especially true where such films are employed in the motion picture art.

.But this adhesion ought not to be obtained at the expense of uniformity inthe product, that is, the steps which promote the bonding Other objects will of the layers ought not. to impair or wash,

away any of the layers themselves. This is especially important where the sensitive photographic coating is not-applied directly to the base, butis coated, onto a gelatinous bonding substratum previouslydormed on formed .onilaminated film supports in which the cellulosic layer pn the face nearest the liably solved by correlating the formation of the thin cellulosic layer and the formation of the substratum. The cellulosic coating is formed by applyin a dope or varnish to the main layer of the ass. From thiscoating part of the volatile liquid is evaporated to stabilize it; and then there is applied to it a gelatinous substratum-forming composition insuficient to remove the partially stabilized coating, but including 'sufiicient volatile solvent to promote adhesion between it and the coating. Anyresidue of volatile liquid in the cellulosic coating and the volatile liquid in the substratum are finally evaporated simultaneously to produce an especially strong interunion.

The principle of such procedureis of general applicability wherever a gelatino-silver halid'emulsion layer has to be united by.

means of a substratum layer to a cellulosi'c varnished or thinly coated face of a support.

Moreover this principle applies whether the cellulosic layers, coatings, and varnishes'of the base or support be composed "of such compounds as cellulose nitrate, cellulose acetate, cellulose ether, or various mixtures of them with orwithout softeners. Since, however, the'principle is especially valuable in preparing thefilm described in my hereinabove cited prior application, I shalldescribe the application of it to the manufacture of such film; but it will be understood that this is done by way of illustration, and thatthe described steps are equally applicable to the preparation of other films, the manufacture of :which presents the same. broad problem.

Referring to the accompanying drawing, a sheet or band 1 of cellulose acetate composition (such-for instance asihat disclosed in U. SQ PatentNo. 1,342,601, Seel, June 8, 1920) which is to form the main layer of the film base is passed over any suitable guiding and propelling means, such as the roller 10, which carries it over any suitable coat: ing means, such as roller 11, partially immersed in a bath 12 of nitrocellulose solution or varnish, the nitrocellulose being of the known coatable types used in films, lacquers,

and photography.

Thisv varnish may, forxinstance, he similar to the one disclosed in my hereinabove cited prior application, and, therefore, contain 100 parts of nitrocellulose dissolved in 30 to 100 parts of fusel oil or butyl alcohol and 400 to 5000 parts of a mixture of acetone and' methyl alcohol in varying relative proportions, say equal parts by weight.

When the reduction of inflammability is of importance, as in the preferred film described in my hereinabove cited application, there is also added to this dope or varnish 10 to parts of triphenyl phosphate. 'As

will be understood by those skilled in the art, the above varnish can be thinned out even further to obtain greater fiowability by the addition of still more acetone and methyl alcohol,-or even by the addition of some diluent like ethyl alcohol. It is flowable so as to be especially convenient for application by means of a coating wheel, as indicated at 11. Of course, any other equivalent known coating expedients can be sed in place of a wheel, such as slotted troughs,

belts, coating brushes, spraying apparatus, etc. i v p he layer 1 carrying the coating of nitrocellulose 2 next moves towardguiding or in the solution of the hereinabove described problem. In fact a usuable unsealed film can be made by omitting it and merelyfol-v lowing the hereinafter described procedure. The hardening of the coating during its passage between the wheels 10 and 13 may, of course, be hastened by the application of heat, currents of drying gas, or other well known expedients, as will be understood by those skilled in the art without further de- 4 e scriptlon. V s

' When the layer 1 bearing the coating 2 passes around the wheel 13, its uncoated face is outward and held evenly so that. it is adapted to receive a uniform coatin 3 by any suitable means, here illustrate as a roller 14 turning in bath .15. The latter a may have the same composition as that of bath 12 described heremabove. Layer 1 1,5e'asie carrying the hardened layer 2 and the still uncured or somewhat plastic layer 3 then passes to suitable iding on propelling means 16, which may 11 ewise be a roll havinga smooth supporting periphery, cooperatlng with coating roll 17. The above mentioned rolls may ofcourse be power driven, and the speeds of the rolls may be individually adjustable as-well as the spacing of the coating rolls from the film, known coating machine practice being followed in these respects.

As the coated fihn base or support passes toward roll 16, the coating 3 starts to set or harden because of the eva oration of the volatile liquids from it. This may be assist ed, if desired, by the application of heat or currents of drying gas. The evaporation is not, however, carried through to the point where the coating 3 becomes fully hardened. It should'still be in a somewhat uncured or partially undried state when it reaches roll 16. This enables it to receive the, sub- -stratum-forming liquid without being washed away by the latter, and still be in a state to promote adhesion. Its partially set condition, in which it thus resists washing away and yet promotes adhesion,- is conveniently termed a. partially stabilized state. While adhesion can be effected to a degree that is sometimes usefulwhen ouring has taken place, nevertheless, the adhesion is stronger and the process is faster when the substratum is applied to a coat- ,ing which is only partially stabilized.

As the film base or sheet passes'below the roll 16, a substratum forming liquid is applied to the partially stabilized layer 3 by any suitablemeans, such as a coating roll 17, turning in bath 18.

The substratum-forming composition is preferably of a kind described in U. S. Patent No. 550,288, Penniman, Nov. 26, 1895. It may, for example, consist of gelatine in a liquid containing .a solvent of celluloid, such as acetic ether or other well known equivalent volatile nitrocellulose commercial solvents. The gelatinous li uid is preferably kept dilute (say imder ve per cent of gelatine) so as to have aneasy flowing capacity, the strength being a matter of routine adjustment by any one skilled in the art to meet slightly varying conditions. The thicker the solution employed. the faster the filmband should pass over roll 17, and the slower the roll 17 should feed.

The thicker layer 3 is. the thinner the gelatinous solution may be. Of course, if the layer 3, to which the substratum 4 is to adhere, be composed of a different cellulosic material from nitrocellulose, corresponding known volatile solvents of such material will be substituted in the substratum in place of the nitrocellulose solvents -mentioned by Penniman.

By adjusting roll 17, the substratumforming composition is ap lied in the right quantity to avoid the eating out or washing. awa of the partially stabilized coat ing 3. g s the film band passes away from rolls 16 and 17 the volatile liquids remaining inlayer 3, as well as the volatile liquids in the substratum 4.- evaporate together. It

has been found that this siinultaneousevaporation, carried out under the described con-' dition's, efl'ects an especially durable bond between the strata without impairing the latter. The evaporation may, of course, be

conducted by heating, or currents of drying. gas, or other expedients well known in the art. At all points where volatile solvents are evaporated, the vapors may be conducted away and recovered in the ways known in the art. When the evaporation of volatile liquids from coating 3 and substratum 4 has reached such a point that the convolutions will not stick together or be impaired by intercontact, the sheet or mm 1 may be rolled up for storage, or the gelatino-silver halid emulsion may optionally be applied imme- 1 diately to substratum 4, as at coating 5 I claim as new and desire to secure by Letters Patent is:

1. In the process of making a film having a gelatinous layer attached by a substratum to a-laminated support which has a coating of c'ellulosic material on a main layer, the steps of forming said'coati'ng by applying to said main layer a relatively thin coating of cellulosic material dissolved in a volatile liquid which contains a solvent of said main layer to promote adhesion between said. coating and layer, partially stabilizing said coating by evaporating a portion of said liquid therefrom, applying over said par tially stabilized coating a gelatinous substratum-forming composition, insuflicint to remove said coating, said composition including a volatile liquid containing a solvent of 'said coating to promote adhesion between it and said substratum, and simultaneously evaporating said volatile liquids from said superposed coating and substratum.

2. In the process or makings film having 1 a photographic gelatinous'layer attached by a substratum to a coating of nitrocellulose on a main cellulosiclayer, the steps of applying to said main layer a relatively thm coating of nitrocellulose dissolved in a liquid which contains a solvent of said main layer to promote adhesion between said coating and layer, partially stabilizing said coa-tin by evaporating a portion of said liquic l therefrom, applying over said partially stabilized coating a gelatinous substratumforming composition insufiicient to remove said coating, said composition. including a volatile liquid containing a nitrocellulose solvent to promote adhesion between said coating and said substratum, and simultaneously evaporating said volatileliquids from said superposed coating and substratum.

3. In the process of making a'film having a light senstive gelatino-silver-halid layer attached by a substratum to. a nitro cellulose coating on a main acetone-soluble cellulose acetate layer, the steps of applying to said main layer a relatively thin coating of nitrocellulose varnish containing acetone to promote adhesion between said coating and main layer, partially drying said coating, applying over said partially dried coating, a gelatinous, substratum-forming liquid composition insufiicient toremove said coating but containing. a volatile nitrocellulose solvent to promote adhesion between said coating and said substratum, and drying together said superposed coating and substratum.

4. In the process of making a. film having a light sensitive gelatino-silver-halid emulsion'layer attached by a substratumto a coating of cellulose-ester on amain cellulosic layer, the steps of applying to said main layer--a relatively thin coating of cellulose ester dissolved in a volatile liquid which contains asolvent of said main layer to promote adhesion between said coating andlayer, partially stabilizing said'coating by partially evaporating said liquid, applying over said partially stabilized coating a gelatinous substratum-forming composition insufficient to remove said coating, said composition including a volatile liquid containing a solvent of said coating to prorfiote adhesion between it and said substratum, si-

multaneously evaporating said volatile liquids from said superposed coating and substration and coating a light sensitive gelatino-silver-halid emulsion over said substratum. r

Signed at Rochester, New York this 9th day of April, 1924.

JAMES H. HASTE. 

